Return to resource list after adding/removing an item from a lesson/quiz

[MisRob]

Summary

Redirect coaches to a list after adding or removing an item from a lesson/quiz when planning a class. Display snackbar on a list page.

Lesson	Quiz

Reviewer guidance

Lesson

• Coach -> Plan -> Lessons -> select a lesson/create a new lesson -> MANAGE RESOURCES -> open a resource preview
• Click ADD/REMOVE

Quiz

• Coach -> Plan -> Quizzes -> create a new quiz -> open a resource preview
• Click ADD/REMOVE

References

Closes #6819
Opened #7212

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Contributor Checklist

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• PR has the correct target branch and milestone
• PR has 'needs review' or 'work-in-progress' label
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• If this is an important user-facing change, PR or related issue has a 'changelog' label
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Testing:

• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical user journeys are covered by Gherkin stories
• Critical and brittle code paths are covered by unit tests

Reviewer Checklist

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md

[codecov]

Codecov Report

Merging #7213 into release-v0.14.x will increase coverage by 0.06%.
The diff coverage is 0.00%.

Impacted Files	Coverage Δ
.../src/views/plan/LessonContentPreviewPage/index.vue	0.00% <0.00%> (ø)
...c/views/plan/LessonResourceSelectionPage/index.vue	0.00% <0.00%> (ø)
...c/views/plan/PlanLessonSelectionContentPreview.vue	0.00% <0.00%> (ø)
...oach/assets/src/views/plan/PlanQuizPreviewPage.vue	0.00% <0.00%> (ø)
kolibri/core/query.py	69.09% <0.00%> (-8.47%)	⬇️
kolibri/plugins/default_theme/kolibri_plugin.py	92.30% <0.00%> (-7.70%)	⬇️
kolibri/core/theme_hook.py	48.30% <0.00%> (-1.70%)	⬇️
...ugins/device/assets/src/modules/wizard/handlers.js	8.73% <0.00%> (-0.15%)	⬇️
.../core/deviceadmin/management/commands/dbrestore.py	76.56% <0.00%> (ø)
...plugins/facility/assets/src/views/UserEditPage.vue	0.00% <0.00%> (ø)
... and 8 more

[jonboiser]

We should prevent the Preview pages changing in appearance before navigating back to the resource-list page (see GIF).

Could you

1. Remove the "Added" indicator from appearing
2. Prevent the button label from switching from "Add" <-> "Remove" before redirect happens
3. (Optionally) disable the button to discourage double-clicking the button (even though double-clicking does not appear to cause problems)

[jonboiser]

I also added some suggestions for fixing #7212 inside some comments

[MisRob]

Hi JB, thank you. I've just pushed all updates.

Regarding "Added" indicator, although it's not rendered after "Add" button click anymore, it's still displayed on the preview page load - is it fine or do you want to remove it completely? I've tried both options and it seems that keeping indicator for this situation makes visually clear if it's added or not at first glance when compared to displaying "Remove" button only.

[MisRob]

Also added a commit to unify snackbar messages that closes #7212.

[MisRob]

This watcher is not currently used though I added it because I would expect that disableSelectButton will be appropriately reset on selection state change.

[jonboiser]

The changes look great, thanks!

[jonboiser]

@MisRob I found a bug where if you removed the only resource in a lesson from the preview page, it would be automatically re-added when navigating back to the resource list (due to the complicated autosaving logic we use). I added one more commit as a hack to fix this by committing the resource removal before the navigation, but keeping the Preview page buttons and indicators saying "added" until the navigation occurs.